1. Technical Field
The present invention relates to a projection system for enlarging and projecting an image displayed in an image display apparatus, a projector using the projection system, and a conversion lens for a projector.
2. Related Art
As a projection system of a projector, it is known to change the position of a lens to change the curvature of the image plane for image projection on a curved surface other than a flat surface (see WO2013/80953, for example). Further, there is a known projector in which a shape-variable mirror or a non-rotationally-symmetrical lens is provided as part of an optical system that forms the internal section of the main body of a projector for geometrical correction of an image projected on a screen (see JP-A-2006-178155, for example).
In a case where projection is performed on a screen that is not rotationally symmetrical with respect to the optical axis of a projection system, for example, a cylindrical surface, for example, the image formation position in the vertical direction of the screen differs from that in the horizontal direction of the screen. The image formation state therefore varies depending on the position on an image. As a result, high image formation performance over the entire image cannot always be achieved.